High voltage by-pass switch



Oct 16. 1956 c. v. NEWBILL 2,767,282

HIGH VOLTAGE BY-PASS SWITCH Filed on. a, 1954 IIMIJVI ZZZMJM United States Patent HIGH VOLTAGE BY-PASS SWITCH Carl V. Newbill, Portland, Oreg.

Application October 8, 1954, Serial No. 461,089

2 Claims. (Cl. 200-118) This invention relates to a by-pass switch for high voltage electric circuits and has particular application to electric signs and the like having a plurality of gas filled tubes connected in series. The present invention comprises improvements over those described and claimed in my United States Letters Patent No. 2,464,340 and No. 2,479,179.

Primarily, the object of the invention is to provide an improved by-pass switch for shunting a high voltage circuit around a piece of equipment which has become non-conductive and formed a break in the normal operating circuit.

More specific objects of the invention are to provide an improved by-pass switch for gas-filled electric sign tubes and the like connected in series, to provide improved arc-responsive means for shunting the electric circuit around a tube which has become inoperative; to provide by-pass means mounted on or incorporated in individual units of an electric sign, and to provide a novel form of by-pass switch for the purpose described which is inexpensive to manufacture and more safe and practical in use than conventional devices.

The above objects are accomplished, for example, by sign units, hereinafter explained in detail, each comprising a tube for neon or other gas and having enclosing structure for a thermally responsive switch. The enclosed switch is thermally responsive to the formation of an are for shunting the electric current in the supply wires around a defective sign unit by means of a bypass circuit. Integration of the switches with the sign units makes the whole assembly less expensive to manufacture and install and safer in operation than previous devices.

The invention will be better understood and additional objects and advantages will become apparent from the following description taken in connection with the accompanying drawings. It is to be understood, however, that the invention may take other forms and that all such modifications and variations within the scope of the appended claims which will occur to persons skilled in the art are included in the invention.

In the drawings:

Figure 1 is a schematic view of a sign installation embodying the invention;

Figure 2 is a longitudinal sectional view through one end of a sign unit and showing the structure of one form of the thermally responsive switch during normal operation of the sign unit;

Figure 3 is a sectional view taken on the line 33 of Figure 2;

Figure 4 is a sectional view similar to Figure 3, but showing the switch after it has operated in response to failure of the sign unit;

Figure 5 is a longitudinal sectional view of a sign unit equipped with an attached switch housing.

Referring in detail to the drawings, Figure 1 shows a representative installation of a sign employing a plurality of individual sign units comprising ga-s filled glass 2,767,282 Patented Oct. 16, 1956 tubes which are bent to form letters, words or designs. Three of such tubes are shown in Figure l and are designated by the numerals 10, 11 and 12. The gas filled tubes 10, 11 and 12 are mounted in a sign casing 13 in the desired arrangement, and are energized by high voltage electric current from a pair of supply wires 15 and 16 connected to the secondary of a transformer 17, the transformer primary being fed from a pair of line wires 18 and 19. The gas filled tubes are provided with the conventional pair of electrodes 21, each having a lead wire 22 which supports the electrodes in the tubes and which electrically connects the electrodes in the sign circuit. Supply wire 15 from the secondary of the transformer 17 is connected to electrode wire 22 on one end of the sign and supply wire 16 is connected to the electrode wire 22 on the opposite end of the sign. The sign units 10, 11 and 12 are connected in series by wires 24 connected to electrode wires 22 of adjacent ends of the tubes. The structure and circuit thus far described are conventional.

Referring in detail to the embodiment of Figure 2, each of the tube units is formed with an extending switch end or housing 26 having a neck portion 27 and a chamber 28 closed by a plug 29. Neck portion 27 has a central bore 30 and a plug 29 has a bore 31 to receive and support the electrode wire 22, the latter being sealed in bore 30 in the usual manner.

One form of thermally responsive switch 35 is shown in detail in Figures 2, 3 and 4. The switch 35 comprises a pair of spaced insulators 36 supported on the electrode wire 22 within the chamber 28. The insulators 36 are held in spaced relation by a sleeve conductor element 37 having inwardly turned flanged ends 38 which engage corresponding peripheral grooves 39 on insulators 36. Sleeve 37 has a fusible inner liner or band 40 of conducting material. Connected to sleeve 37 is one end of a shunt wire 41 which passes through an aperture 42 in the switch end 26. The other end of wire 41 bypasses the tube and is electrically connected to the electrode wire at the other end of that same tube as shown in Figure 1.

In normal operation of the sign, when the gas filled tubes are operating properly, current will flow through the series circuit of the tubes, the voltage across any one tube being insufficient to produce an are from electrode wire 22 to the conducting fusible liner 40. When one of the tube units becomes inoperative and substantially non-conductive the increase in voltage across such tube will cause an arc to jump from the electrode wire 22 to the fusible liner 40. Liner 40 will fuse from the heat of the arc and form a direct metallic path for current from electrode wire 22 to the by-pass wire 41, thereby shunting the inoperative or partially inoperative tube and the remaining units in the series circuit will remain in operation.

The gap between the inner periphery of the fusible liner 40 and the electrode wire 22 is of predetermined distance whereby an arc will not span said distance under normal voltage drop across a single sign unit but will span said distance when the voltage is increased such as when that particular sign unit becomes defective.

Figure 5 shows a modified form of structure which is designed to be mounted on an existing tube 45. This device comprises a tubular cap 46 which is adapted to be fitted over and secured rigidly to one end of the tube. The thermally responsive switch 35 is mounted on the electrode wire 22, as shown in Figure 2, and has its by-pass wire 41 passing through an aperture 47 in the cap 46. By the use of this modified form, a presently existing sign can be equipped with by-pass means for its individual sign units to prevent the entire sign from becoming inoperative when only a single unit is defective.

A feature of the different embodiments is that the switch means is housed in an integral or attached portion of the sign unit structure whereby the cost of wiring and installation is reduced. The housing of the switch means in a rigidly supported enclosing structure confines the heat of the arc to the illuminating tube units themselves and the switch means do not have freedom of movement after installation to fall at random against combustible materials and create a fire hazard. It will be observed, further, that the device is operable in any position. It is immaterial whether the electrode wire 22 be disposed horizontally, vertically or in an inclined position.

Having now described my invention and in what manner the same may be used, what I claim as new and desire to protect by Letters Patent is:

1. A thermally responsive switch comprising a body member having a chamber therein, an electric supply conductor extending through said chamber, a fusible sleeve of conducting material mounted in spaced relation surrounding said conductor, a conductor sleeve surrounding said fusible sleeve, and a wire connected to said conductor sleeve, whereby the melting of said fusible sleeve will establish electrical connection between said supply conductor and said wire.

2. A thermally responsive switch comprising a supply conductor, a pair of spaced insulating sleeves on said supply conductor, a conductor sleeve encircling said supply conductor and mounted at its ends on said insulating sleeves to enclose the space around said supply conductor between said insulating sleeves, a fusible metal sleeve within said conductor sleeve spaced from said supply conductor, and a wire connected to said conductor sleeve.

References Cited in the file of this patent UNITED STATES PATENTS 1,221,232 Sherman Apr. 3, 1917 1,874,407 Young Aug. 30, 1932 1,971,194 McEachron et a1. Aug. 21, 1934 2,118,437 Kayatt May 24, 1938 2,469,215 Smith May 3, 1949 2,479,179 Newbill Aug. 16, 1949 2,566,648 Worsham Sept. 4, 1951 

